Zuo yuezi, or sitting the month, is a 30-day regimen of food and rest to help new mothers recover from the rigors of childbirth. Skeptics say the claims are unsound.

Ginny Hung, 35, holds her newborn boy Jacob on day 24 after his birth as her… (Al Seib, Los Angeles Times )

Five months into her pregnancy, Jessica Su was already thinking about what she would eat after her baby was born.

On a rainy Saturday afternoon, Su and her husband were sampling soups: pigs feet with dates and peanuts, pork chop with green papaya, beef and carrots with Chinese yam, sesame oil chicken. The makeshift cafe in Walnut was packed with pregnant women helping themselves from metal urns.

Nicole Huang, the tasting event's sponsor, rushed from table to table answering questions posed in Mandarin and English: "Am I allowed to eat fruit?" "Can you provide translations, so I know what I'm eating?"

Su hadn't decided whether she would fork over $2,000 to get Huang's meals delivered to her Buena Park home, or hire a nanny to cook similar foods and tidy the house. Whichever she chose, she planned to observe the Chinese custom of zuo yuezi, or "sitting the month," after giving birth.

According to believers, the monthlong regimen helps women recover from childbirth, produce more breast milk and recalibrate their bodies. In addition to the special diet, new mothers are supposed to rest in bed and avoid contact with water — that is, no shampooing or showering for 30 days.

Skeptics say the health claims are not scientifically sound and that the high-fat, high-protein foods can be harmful to mother and child. Still, the practice is widespread among Southern California's Taiwanese and Chinese immigrants. Families call on companies like Huang's Jing Mommy as a way to follow tradition while sparing themselves from the kitchen.

"You need to do it. All women need to," said Su, a 35-year-old homemaker, of yuezi. "My sister in Taiwan said you really have to or your body will deteriorate. It freaked me out, and I said, 'OK, I'll do it.' "

Yuezi is based on ancient theories of Chinese herbal medicine dividing foods into "warm" and "cold" categories. Each food is linked to a health benefit for new mothers: liver replenishes lost blood, green papaya stimulates milk production and kidney helps with aches and pains.

According to yuezi theory, follicles expand during childbirth, leaving the body vulnerable to cold. Postpartum women are advised to stick to "warm" foods like ginger, chicken and pumpkin.

The prohibition against cold goes beyond diet. In the month after giving birth, women should not wash their hair or go outdoors. Hard-core yuezi observers stick to sponge baths.

After having her first child, Su gave the hair washing ban a try. But she ended up caving, sneaking a shower when her mother, who enforced the rules, was out. This time, she is determined to last the whole month.

"I give it three days," said her husband, David.

Like religion, Yuezi has its true believers and those who follow along just in case there's something to it. Some do it to appease family, while others are mainly interested in the convenience of home-delivered meals.

"At this point, I'm just trying to find food," said Vickie Wu, 35, a physician expecting her first child. "I don't think I believe in it, but it is readily available, and it doesn't seem to hurt."

Besides, Wu's husband, Daniel Sanchez, added, it will make his mother-in-law happy.

Lily Hong, clinical nutrition manager at San Gabriel Valley Medical Center, worries that yuezi doesn't provide enough calcium and that the rice wine and ginger in Chinese soups will be transmitted to breast-feeding babies. She tells new mothers to drink plenty of milk and to choose white meat over innards.

Hong couldn't avoid doing a modified form of yuezi herself, at her mother's insistence, after her two sons were born.

She bathed, and she refused the traditional Cantonese soup of pigs feet and vinegar. She smuggled helpings of boba tea. To keep her mother happy, she ate lots of chicken soup and eggs and didn't leave the house for a month.

"Ginger vinegar soup with pig trotter — to me as a dietitian, I can't stand it," Hong said. "The cholesterol, the saturated fat — I don't think we can pass the Department of Health if we served that kind of soup.

Charlotte Duh, who started the home delivery business Meal4Mom in Temple City three years ago, believes Western women can benefit from yuezi too. Duh would like to attract a broader clientele among those who may already lean toward alternative therapies.

"If you eat the right foods, it'll help a lot. If you're more open to herbs, you'll find they taste really good," said Duh, 40, a licensed acupuncturist who also teaches yoga.